A spindle motor having a hydrodynamic pressure bearing includes a stator, a rotor, and a dynamic pressure generating unit including a sleeve having an upper plate disposed opposite to the rotor and at least one thrust dynamic pressure groove formed either at the upper plate of the sleeve or at the rotor. Inside width from a neutral radius to an innermost radius of the thrust dynamic pressure groove is larger than outside width from the neutral radius to an outermost radius of the thrust dynamic pressure groove such that the neutral radius is biased to the outside of the thrust dynamic pressure groove. Dynamic pressure at the inside width of the thrust dynamic pressure groove is higher than dynamic pressure at the outside width of the thrust dynamic pressure groove such that fluid supplied into the thrust dynamic pressure groove is guided to the outer diameter side.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A spindle motor having a hydrodynamic pressure bearing, comprising: a stator including a coil for generating an electromagnetic field when the coil is supplied with electric current to generate a rotary driving force; a rotor including magnets disposed opposite to the coil such that the rotor is rotatable relative to the stator; and a dynamic pressure generating unit including a sleeve having an upper plate disposed opposite to the rotor while being spaced a predetermined distance from the rotor, the sleeve being fixed to the stator, and at least one thrust dynamic pressure groove formed either at the upper plate of the sleeve corresponding to the rotor or at the rotor for generating dynamic pressure, wherein the inside width from a neutral radius of the thrust dynamic pressure groove to an innermost radius of the thrust dynamic pressure groove is larger than the outside width from the neutral radius of the thrust dynamic pressure groove to an outermost radius of the thrust dynamic pressure groove such that dynamic pressure at the inside width of the thrust dynamic pressure groove is higher than dynamic pressure at the outside width of the thrust dynamic pressure groove such that fluid supplied into the thrust dynamic pressure groove is guided to the outer diameter side.
2. The motor as set forth in claim 1 , wherein the stator comprises: at least one core, on which the coil is wound; and a base having a fixing hole, in which the sleeve is vertically fitted.
3. The motor as set forth in claim 2 , further comprising: a housing fitted in the fixing hole of the stator while the lower end of the sleeve is fixedly inserted in the housing.
4. The motor as set forth in claim 1 , wherein the rotor comprises: a hub disposed opposite to the upper surface of the upper plate, the hub is provided with the magnets; and a stopper ring mounted in the inner surface of the hub, the stopper ring being disposed opposite to the lower surface of the upper plate.
5. The motor as set forth in claim 4 , wherein the hub comprises: a skirt part, to which the magnets are attached; and a shaft extending downward by a predetermined length such that the shaft is fitted in a shaft hole of the sleeve.
6. The motor as set forth in claim 4 , wherein the hub comprises: a skirt part, to which the magnets are attached; and a supporting part formed through the hub for allowing a protrusion formed at the upper end of the sleeve to be inserted therethrough.
7. The motor as set forth in claim 4 , wherein the at least one thrust dynamic pressure groove comprises thrust dynamic pressure grooves formed at the lower surface of the hub of the rotor corresponding to the upper plate of the sleeve or at the upper surface of the stopper ring of the rotor, respectively.
8. The motor as set forth in claim 1 , wherein the at least one thrust dynamic pressure groove is formed in the shape of a herringbone.
9. The motor as set forth in claim 1 , wherein the at least one thrust dynamic pressure groove is formed either at the upper surface or at the lower surface of the upper plate of the sleeve.
10. The motor as set forth in claim 1 , wherein the at least one thrust dynamic pressure groove comprises thrust dynamic pressure grooves formed at the upper and lower surfaces of the upper plate of the sleeve, respectively.
11. The motor as set forth in claim 4 , wherein the at least one thrust dynamic pressure groove is formed either at the lower surface of the hub of the rotor corresponding to the upper plate of the sleeve or at the upper surface of the stopper ring of the rotor.
12. The motor as set forth in claim 1 , wherein the upper plate of the sleeve is provided at the outer circumferential surface thereof with at least one vertical groove.
13. The motor as set forth in claim 12 , wherein the at least one vertical groove is formed at the outer circumferential surface of the upper plate of the sleeve corresponding to the outer end of the thrust dynamic pressure groove.
14. The motor as set forth in claim 1 , wherein the upper plate of the sleeve is provided with at least one fluid circulating part, which is formed through the upper plate from the upper surface to the lower surface thereof.
15. The motor as set forth in claim 14 , wherein the at least one fluid circulating part is disposed either at the inside width of the thrust dynamic pressure groove or in the vicinity of the inside width of the thrust dynamic pressure groove.
16. The motor as set forth in claim 14 , wherein the inside width of the upper thrust dynamic pressure groove corresponding to the upper end of the fluid circulating part is narrower than that of the lower thrust dynamic pressure groove corresponding to the lower end of the fluid circulating part.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 21, 2005
November 13, 2007
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